21623616 has 168 divisors, whose sum is σ = 73542144. Its totient is φ = 5944320.

The previous prime is 21623603. The next prime is 21623617. The reversal of 21623616 is 61632612.

21623616 is a `hidden beast` number, since 21 + 6 + 23 + 616 = 666.

It is a tau number, because it is divible by the number of its divisors (168).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a nude number because it is divisible by every one of its digits.

Its product of digits (2592) is a multiple of the sum of its prime divisors (216).

It is a self number, because there is not a number n which added to its sum of digits gives 21623616.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 124906 + ... + 125078.

Almost surely, 2^21623616 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21623616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36771072).

21623616 is an abundant number, since it is smaller than the sum of its proper divisors (51918528).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21623616 is a wasteful number, since it uses less digits than its factorization.

21623616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229 (or 216 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 21623616 is about 4650.1199984517. The cubic root of 21623616 is about 278.5967891254.

It can be divided in two parts, 2162 and 3616, that added together give a triangular number (5778 = T₁₀₇).

The spelling of 21623616 in words is "twenty-one million, six hundred twenty-three thousand, six hundred sixteen".